There is currently no support for visionOS in any SDK (native C++, Unreal, Unity).

The first step in adding visionOS support across all platforms is creating a native NoesisGUI library for visionOS.
Apple's Metal API is supported on visionOS in certain specific scenarios (2D Window App, 2D Windows in AR Apps, VR Apps). It should be straightforward to port the existing iOS version of the NoesisGUI library which is already using the same Metal API.

In the short term, such a library would allow for:
An eventual NoesisApp for visionOS enabling NoesisGUI UIs in a 2D windows in a visionOS AR or VR app.

Also this library will be required to implement visionOS (VR) support in Unreal and Unity.
Unreal 5.4 VR Support - https://forums.unrealengine.com/t/suppo ... 1190042/40
Unity Windowed Support - https://docs.unity3d.com/Packages/com.u ... dApps.html
Unity VR Support - https://docs.unity3d.com/Packages/com.u ... RApps.html